Telegraphy.



Pafented Oct. 28, I902.

No. 7|l,942.

A. C. DREHORE.

TELEGRAPHY.

(Application. filed Oct. 21, 1901.) (No Model 2 Sheets-Sheet I.

No. 7||,942. Patented Oct. 28, I902.

A. c. casnomz.

TELEGRAPHY. (Application filed Oct. 21, 1901.)

(No Model.) 2 Sheets-Sheet 2.

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UNITED STATES PATENT OFFICE.

ALBERT C. CREHORE, OF TARRYTOWLUNEW YORK.

TELEGRAPHY.

SPECIFICATION forming part of Letters Patent No. 711,942, dated October28, 1902.

Application filed October 21, 1901. Serial No. 79,386. (No model.)

To all whom it may concern:

Be it known that I, ALBERT C. CREHORE, a citizen of the United States,and a resident of Tarrytown, in the county of Westchester and State ofNew York, have invented certain new and useful Improvements inTelegraphy, of which the following is a specification.

My invention relates to those systems of telegraphy known as quadruplextelegraphy, wherein one line serves for the transmission of fourmessages independently of one another, two in one direction and two inthe opposite direction.

In quadruplex telegraphs as at present generally constructed it is thepractice to transmit in the same direction from the terminal station bychanges of current tension and changes of polarity of a continuouscurrent. In these systems great difficulty is frequently experienced inmaintaining the adjustment of the instruments upon all four sides f ofthe system, and, as is well known, the fourth side is generally weak anduncertain in operation. Moreover, in this class of telegraphs specialprovision has 'to be made for preventinga kick in the instrument, whichresponds to changes of tension whenever a reversal of the polarity ofthe current takes place on what is ordinarily termed the No. 1 side ofthe system. I

The aim of the present invention is to provide a quadruplex system whichshall be free from most of the difficulties hitherto experi-. enced inworking quadruplex telegraphs, wherein the receiving instruments at eachstation are rendered insensible or irresponsive to outgoing signals bythe well-known bridge or diiferential system of duplexing; to which endthe invention consists of a novel quadruplex-telegraph system whereinthe transmissions from one station over one side of the system areelfected by the use of a continuous current, and the transmission forthe other side is effected by the pulsatory currents superposed upon thecontinuous currents, the pulsatory-current apparatus being, however,connected to the line and having its receiving. apparatus balanced orrendered neutral to outgoing signals in such manner that any disturbanceof the exact balance of the main and artificial lines shall not produceany disturbance on the continuous-current side from the working of thepulsatory-current side, as hereinafter more fully set forth. In otherwords, in carrying out the invention I utilize as the means for thedouble transmission from each end of a quadruplex line that system oftelegraphy known as the superposed-current system, wherein one-messageis sent by currents from a generator adapted to generate momentarycurrents of short duration and sharply defined or having a high rate ofchange of electromotive force and hereinaftertermed pulsatory currents,and the other message is sent over the same wire simultaneously bycurrents which, generally speaking, are of longer duration andhereinafter termed continuous currents and upon which the pulsatorycurrents are superposed.

It is obvious that I may use on the continuous-current side of thesystem either changes of tension to effect the transmission or changesof polarity, the latter being what is frequently termed thedouble-current system. For the pulsatory-current side of the system Iprefer to use for each signal a succession of pulsatory currents and todetermine the length of the signal by the length of time during whichthe succession of currents is permitted to flow, although as wellunderstood in the art the transmission by the pulsatory-current side ofthe double-transmission system working on the superposedcurrent planmight be effected by the use of two pulsations for each signal separatedby an interval during which no pulsatory currents flow and of greater orless duration, according to the length of the signal to be transmitted.

It will be obvious that if the continuouscurrent side of my system beworked by changes of polarity an additional set of signals might be sentby using also changes of tension, or vice versa, the system thenbecoming, in eifect, a sextuplex, but with the disadvantages attachingto a quadruplex, as hereinbefore stated. In a measure, however, theadvantages of my presentinven tion would be realized, because the thirdtransmission or set of signals could be effected at all times withoutdisturbing the continuous-current I side of the system even though thereshould be any want of balance of. the main and artificial circuit as tothe latter side or sides of the system. v

The main feature of myinvention consists in using for the two sides ofthe system balancing branches derived from independent apexes or pointsof division to which are joined, respectively, the branch or groundconnections containing, respectively, the transmitting apparatus for thetwo sides of the system.

My invention consists also in the combination, with thecontinuous-current transmitting apparatus joinedv to an apex from whichdiverge the balancing branches for the receiver, ofindependent balancingbranches for the receiver of the pulsatory side and an inductance in theground connection containing the continuous-current apparatus, ashereinafter more particularly described.

In the accompanying drawings, Figure 1is a diagram of aquadruplex-telegraph apparatus having its parts connected up at eachstation in accordance with may present invention. Figs. 2 and 3 arediagrams illustrating modifications of the invention.

In carrying out the invention the generators of current may be of anydesired character. For the continuous-current side of the system acontinuous-current dynamo may be employed. The pulsatory-currentgenerator is preferably an alternating-current dynamomachine. Intransmitting by the doublecurrent system on the continuous-current sideI may use a pole changer or reverser which reverses the poles of agenerator in respect to the main line and earth, or I may use any otherdisposition of apparatus known in the art or suitable for the purpose.

NVhile the drawings indicate the use of an alternating-current dynamo asthe pulsatorycurrentgenerator and also show the same connected directlyinto the circuit, it is to be understood that the generator might be ofany form known in the art and that the pulsations might be imposeddirectly or indirectly upon the circuit in any of the ways well known inthe art.

Referring to Fig. l of the drawings, the continuous-current transmissionis shown as effected by What is known as the double-current system, forwhich purpose there is pro vided a continuous-current generator 5 of anydescriptionas, for instance, a continuous-current,dynamoand apole-changinginstrument 1, known as a pole-chan ging trans mittcr, whichmay be operated by means of an electromagnet, as indicated, controlledas usual in the art.

3 typifies the receiver for the continuouscurrent side of the system,This instrument is rendered neutral as to outgoing signals in the usualwayas,forinstance, by providing a... M H. J

it with two windings, known as dilferential windings, one of which is ina branch leading from an apex or pointof division 20 to the line L,while the other or balancing winding is in a branch from the same apex,connected to an artificial line containing the usual condenser 15'andadjustable rheostat 16 17, employed, as well understood in the art, foradjusting the resistance and capacity of the artificial line 18 so thatit will equal that of the main line L.

The transmitting apparatus, comprising generator 5 and instrument 1, isconnected on one side to earth, as usual, and on the other to the apex20'. In the latter connection I preferably interpose a suitableinductance 12, made, as well understood in the art, by winding a coil ofwire upon a core whose magnetic circuit is preferably closed, so thatthe device may have a high impedance for pulsatory currents or currentshaving high rate of change and low resistance for the continuouscurrent.

The transmitting apparatus for the pulsa- Lory-current side of thesystem,as here shown, embraces the transmitting instrument 2 andpulsatory-current generator 6, typified as an alternating-currentdynamo] These devicesIare in an independent branch connected tojearthand are joined, as shown, to an independent point of division or apex21, from which branches are taken, respectively, to the line L and tothe artificial line 18 through condensers.

The receiving instrument for the pulsatorycurrent side of the system isrendered neutral to outgoing signals by the balancing effects producedby means of the two branches leading from apex 21 to the lines Land 18in any desired way-as, for instance, by the differential plan; but ineach branch there is placed a condenser 8 to permit pulsatory currentsto flow freely, while obstructing the fiow of the continuous current. Atthe apex 21 an adjustable resistance 14 may be located, which isadapted, as indicated, to change the relative resistance of the branchesas may be required and in a manner to increase the resistance in onebranch and simultaneously decrease the resistance in the other, or viceversa.

The pulsating-current receiver 4 is preferably a polarized instrument inorder that it may be more sensitive to the pulsating current.

As will be seen, the pulsatory currents transmitted to the distantstation may flow freely through the condensers to the line L, while theequal but opposing similar currents balancing the eifects of the formerflow through the other branch by condenser 8 to the artificial line 18.Moreover, such currents may not How through the branches leading fromthe apex 20 for the continuous-current receiver or receivers. At thesame time the continuous currents sent by transmitter 1 may flow andhave their effect balanced in receiver 3 independently, since they maynot pass by way of condensers 8 to earth.

It willbe seen that in the arrangement shown there is a return path forthe pulsatory current back to generator 6 independently of the lines Land 18 by way of the branch to earth through the continuous-currentapparatus. This path may be traced from the points of junction of thetwo condenser branches with the main line L and artificial line 18 backthrough the two coils of receiver 3 to apex 20 and by way of reactanceor inductance 12 through the transmitting apparatus for thecontinuous-current side of the system and to earth. If the main andartificial lines L 18 are exactly balanced and the potential fromgenerator 6 at the points of junction of the pulsatory-current brancheswith the lines L and 18 are substantially equal, then such pulsatorycurrents as may be able to force their way back to earth through thebranch or earth connection afforded by the balancing branches for thecontinuous-current apparatus and the inductance 12 will .be balanced onthe receiver 3 and. no disturbing action will result. If at any time adisturbance in the balance of resistance of the lines L 18 arises, sothat more pulsatory current would flow back over one branch of thecontinuous-current side and through the other by the path alreadytraced, the reactance of 12 operating to cut off the tendency of thepulsatory current to flow by such path will soreduce the value of anysuch want of balance that the instrument 3 will be practicallyunaffected by the pulsatory current at the same station. Hence if allbalance of the lines L and 18 should fail, so that both thepulsatory-current and continuous-current receivers respond to their owntransmitters, there will still remain a duplex-diplex system oftelegraphing, for the continuous-current receiver will still not respondto the pulsatory-current transmitter at the same station because of theimpedance or reactance afforded by inductance l2, and

the pulsatory-current receiver will not respond to thecontinuous-current transmitter at the same station because of thecondenser 8. Hence two messages may be still sent'either in the same orin opposite directions, one by the pulsatory and the other by thecontinuous current. In this respect the apparatus possesses an importantadvantage over ordinary quadruplex or duplex systems, in which thefailure of balance renders it necessary to work the line single only.

Instead of balancing the outgoing signals by the difierential method itis obvious that the bridge method might be employed, as indicated inFig. 2, in which case each branch from the apex 21 to lines L 18contains a condenser 8, and the instrument I is located in a bridge fromthe line L to artificial line 18, as shown, said bridge, however,containing a condenser 8 to prevent the continuous currents from beingshort-circuited from the continuous-current receiver in receivingmessages. The condensers 8, while having the function already described,operate also by their location to prevent the incoming pulsatorycurrents from being short-circuited around the instrument 4:.

The independent branch containing the pulsatory current transmittingapparatus need not be connected directly to earth in the manner shown inFigs. 1 and 2, but may be connected through the continuous-currenttransmitter in the manner shown in Fig. 3, wherein the terminal of thebranch instead of leading directly to earth leads to the circuit orconnection between the continuouscurrent transmitter and the inductance12.

In this diagram the receivers are indicated in skeleton, their two coilsbeing shown separated from one another as located in the separatebranches leading from the apexes 2021, respectively,and as indicated bythe numerals 3 4. This is substantially the arrangement illustrated inFig. 1. The inductance 12, Fig. 3, operates in the same manner as theinductance already described.

What I claim as my invention is 1. In a multiplex-telegraph apparatusfor multiple transmission in opposite directions, the combinationsubstantially as described, of pulsatory-current and continuous-currenttransmitting and receiving apparatus, independent balancing branches forthe'continuous-current and pulsatory-current receivers, independentground branches or connections for the continuous-current andpulsatory-current transmitting apparatus respectively,and independentapexes or points of division to which said ground branches are connectedand from which the aforesaid balancing branches for thecontinuous-current and pulsatorycurrent receivers respectively arederived.

2. In a quadruplex-telegraph apparatus the combination for the two sidesof the double transmission at each station, of continuouscurrent andpulsatory current apparatus, balancing branches for both sides of thesystem, ground branches or connections from which said balancingbranches are derived, and an inductance in the ground branch orconnection for the continuous-current side as and for the purposedescribed.

Signed at New York city, in the county of New York and State of NewYork, this 16th day of October, A. D. 1901.

ALBERT C. CREI-IORE.

Witnesses:

J. GALLWITZ, E. L. LAWLER.

